The present invention is related generally to the art of foldable trailer ramps, and more specifically to a readily removable and hydraulically powered foldable ramp which is intended for use in connection with standard general purpose draft vehicles, such as flatbed trailers.
Building contractors and others are, from day to day, continually faced with the problem of transporting large pieces of ground-moving equipment and machinery from one job site to another, in a cost-efficient and timely manner. This problem has lead many contractors to purchase highly specialized and expensive trailers for transporting such equipment. Such specialized trailers are generally constructed with an unusually low-profile trailer bed which enables the operator to use a relatively short ramp with a low angle of incidence to the ground for loading large pieces of equipment.
Such specialized trailers, however, are generally designed for the specific purpose of transporting large industrial equipment, and are not well suited for use in transporting other commonly used machinery and construction materials. While such trailers have been effective in enabling the efficient transport of such large equipment, the cost of such trailers is prohibitive in relation to that of a conventional flatbed trailer. Examples of such trailers can be found in U.S. Pat. Nos. 3,779,411; 4,305,694; and 4,372,727.
The fruition of such specialized trailers stems from problems experienced with the use of conventional flatbed trailers. The elevation of the bed of a standard flatbed trailer is such that, unless the connecting ramp is substantially lengthened, the grade of the ramp will be undesirably steep for loading such large equipment. While lengthening the ramp to lower its angle of incidence to the ground has been successfully implemented in the past, such ramps are generally excessive in weight and include multiple folding sections which are unduly cumbersome to manipulate between a loading and transport position. For this reason, such ramps are generally hydraulically controlled and permanently attached to the rear of the flatbed trailer to avoid the difficulty in manipulating the excessive load caused by the elongated ramp.
One foldable ramp which is detachable from a trailer bed is shown in U.S. Pat. No. 5,678,984. It is readily apparent, however, that such ramp, consisting of multiple foldable sections and constructed to be hydraulically operated, cannot be mounted or removed from the flatbed trailer without the use of additional power equipment or at least two workmen to lift and position the same for mounting on, or disconnection from, the rear of the flatbed trailer. Thus, such ramp is basically unusable unless sufficient manpower is present to mount or remove the same, which is oftentimes not the case.
Thus, there is a need for a foldable ramp which, when unfolded into a loading position, is of sufficient length to provide a low-grade ramp surface, while at the same time being readily mountable and removable from the rear of a flatbed trailer without the need for excessive manpower to accomplish the same. It is with this objective in mind that I have conceived of my new hydraulically foldable and elevationally adjustable ramp which incorporates a self-contained hydraulic power and control source for independent ramp positioning, to facilitate ease of mounting and removal thereof from the rear of a flatbed trailer.
In accordance with the present invention, described herein is an elongated hydraulically foldable ramp having an elevational adjustment means for facilitating efficient connection and removal of the ramp to a conventional draft vehicle, such as a flatbed trailer. The ramp includes at least a pair of ramp sections, one section constituting a leading ramp section and the other section constituting a trailing ramp section. The forward end portion of the leading ramp section is constructed for pivotal connection to the rear of the flatbed trailer. The forward end portion of the trailing ramp section is pivotally joined with the rear end portion of the leading ramp section, thereby defining an axis of pivot about which the leading and trailing ramp sections may pivot for movement between a generally aligned, inclined loading position and a substantially upright, closely parallel traveling position.
The ramp further includes a ground-bearing pad which is pivotally connected and depends freely from the ramp at a point adjacent the axis of pivot between the leading and trailing ramp sections, and forward of the center of gravity of the ramp. This ground-bearing pad is thus inherently gravitationally positionable, and constructed and arranged such that it engages the ground and provides support to the ramp sections when the ramp is disposed in a loading or stored position. As will be explained hereafter, the ground-bearing pad is also instrumental in providing elevational adjustability of the forward end portion of the leading ramp section to facilitate mounting of the ramp to, and removal thereof from, the rear of a flatbed trailer.
As used herein and throughout the appended claims, the term xe2x80x9cgravitationally positionablexe2x80x9d is meant to convey the ability of the ground-bearing pad to inherently position itself through the effects of gravity thereon, as a result of its freely depending pivotal connection to the ramp.
Hydraulic operation and positional control of the leading and trailing ramp sections are controlled by a pair of hydraulic cylinders connected thereto. The first hydraulic cylinder is connected between the rear end portion of the leading ramp section and a generally vertically extending support member that is pivotally carried by and depends from the forward end portion of the leading ramp section. This cylinder, when activated, controls pivotal movement of the leading ramp section relative to the flatbed trailer when it is connected thereto.
The second hydraulic cylinder is pivotally connected between the trailing ramp section and the leading ramp section, and controls the relative pivotal movement therebetween. Activation of this cylinder in one direction causes the leading and trailing ramp sections to fold together into a transport position, and activation of such cylinder in the opposite direction, with the ramp in its inclined loading or stored position, causes elevational adjustment of the forward end portion of the leading ramp section in the manner described hereafter.
As noted earlier, the ground-bearing pad is connected to the ramp forward of its center of gravity. Thus, the majority of the ramp""s weight is centered toward the rear of the ramp, and the ramp naturally tilts that direction when resting in its inclined loading position. Upon appropriate directional activation of the second hydraulic cylinder, the leading ramp section is caused to pivot relative to the trailing ramp section and raise the forward end portion thereof above the level of the flatbed trailer. Supported by the ground-bearing pad and counterbalanced by the weight of the ramp on the side of the trailing ramp section, the forward end of the leading ramp section will remain in an elevated position, allowing the trailer to either be positioned for mounting of the ramp, or disconnection of the ramp therefrom.
Whether the flatbed trailer is being positioned for mounting of the ramp, or disconnection therefrom, elevation of the forward end of the leading ramp section can be accomplished with minimal effort through the use of the ramp""s own hydraulics. To further facilitate the mounting and removal of the ramp, the hydraulic power source for the ramp is self contained on the ramp for independent operation and positional control thereof. Because the ramp""s hydraulics are devoid of connection to the flatbed trailer, both the ramp and the trailer may be freely adjusted and maneuvered separate from the other to effect proper positioning for mounting of the ramp to, and disconnection of the ramp from the flatbed trailer.
In order to extend the length of the ramp further, and consequently lower the grade of the ramp""s incline, it is contemplated that an additional section may be pivotally connected to the rear end portion of the trailing ramp section. This extension ramp section is preferably smaller in size than the other ramp sections, and can be readily maneuvered by hand without the need for additional hydraulic controls.
With the forward end of the foldable ramp connected to and supported by the flatbed trailer, the ramp""s hydraulics may then be activated to fold and unfold the leading and trailing ramp sections between an aligned, inclined loading position and a substantially upright transport position, as desired.
These and other objects and advantages of the invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which: